public static IType GetElementTypeFromIEnumerable(this IType collectionType, ICompilation compilation, bool allowIEnumerator, out bool?isGeneric)
{
bool foundNonGenericIEnumerable = false;
foreach (IType baseType in collectionType.GetAllBaseTypes())
{
ITypeDefinition baseTypeDef = baseType.GetDefinition();
if (baseTypeDef != null)
{
KnownTypeCode typeCode = baseTypeDef.KnownTypeCode;
if (typeCode == KnownTypeCode.IEnumerableOfT || (allowIEnumerator && typeCode == KnownTypeCode.IEnumeratorOfT))
{
ParameterizedType pt = baseType as ParameterizedType;
if (pt != null)
{
isGeneric = true;
return(pt.GetTypeArgument(0));
}
}
if (typeCode == KnownTypeCode.IEnumerable || (allowIEnumerator && typeCode == KnownTypeCode.IEnumerator))
{
foundNonGenericIEnumerable = true;
}
}
}
// System.Collections.IEnumerable found in type hierarchy -> Object is element type.
if (foundNonGenericIEnumerable)
{
isGeneric = false;
return(compilation.FindType(KnownTypeCode.Object));
}
isGeneric = null;
return(SpecialType.UnknownType);
}
/// <summary>
/// Returns the element type, if <paramref name="type"/> is a nullable type.
/// Otherwise, returns the type itself.
/// </summary>
public static IType GetUnderlyingType(IType type)
{
if (type == null)
{
throw new ArgumentNullException("type");
}
ParameterizedType pt = type.SkipModifiers() as ParameterizedType;
if (pt != null && pt.TypeParameterCount == 1 && pt.GenericType.IsKnownType(KnownTypeCode.NullableOfT))
{
return(pt.GetTypeArgument(0));
}
else
{
return(type);
}
}